Mexican researchers said Wednesday they have identified jaw bones found in the pre-Hispanic ruins of Teotihuacan as those of wolf-dogs that were apparently crossbred as a symbol of the city’s warriors.

The National Institute of Anthropology and History said the jaw bones were found during excavations in 2004 and are the first physical evidence of what appears to be intentional crossbreeding in ancient Mexican cultures.

The jaw bones were found in a warrior’s burial at a Teotihuacan pyramid. Anthropological studies performed at Mexico’s National Autonomous University indicate the animal was a wolf-dog…